Le visage, le masque et le temps. Histoire naturelle de l'architecture segmentaire de la face. Discussion

Extending from the supra-occipital region down to both clavicles, the face is an original anatomical entity which constituTes the main field of interaction between the brain and the external world. We here demonstrate that essential structures arise from the neural crest cells and that the segmental migratory pathway of these cells leads to the segmental ontogenesis of the head, and of the anterior neck area from seven distinct morphogenetic units which enjoy each of an independEnt growth potential. In the adult, the neural and segmental origin of the face is temporarily masked by the superficial musculoaponevrotic system which supports its cutaneous cover. Nevertheless, this fundamental architecture appears fugitively in the mimics of facial expression, then more obviously in the ptotic and folding phenomenons involved in cephalic skin ageing.